GB1023594A - Improvements in or relating to automatic devices,applied to sewing machines,for feeding fabric - Google Patents

Abstract

1,023,594. Sewing machines. NECCHI S. p. A. Jan. 1, 1964 [April 11,1963], No. 43/64. Heading D1G. A group-stitch sewing machine is combined with work-feeding means comprising a first carriage driven to position the work at successive sewing positions, and a second carriage slidable to follow the movements of the first carriage and to move relatively thereto during group-stitching operations, the arrangement being such that a series of group-stitching cycles is performed automatically at predetermined distances apart, and the carriages are then returned to their initial positions. A group-stitching machine 2, mounted on a stand 1, is driven by a motor MAS via a belt 4 which is shifted from a loose to a fast pulley by a linkage 5 on energization of a solenoid EM1, On termination of a stitching cycle, a pattern cam 7 acts on linkage 5 to return the belt to the loose pulley. The work-feeding foot 11 is lifted at the end of a cycle by a solenoid EM2, which simultaneously closes a microswitch MS1. The work is secured between clamps 13 and 14. Clamp 14 comprises a carriage 15 slidable to and away from clamp 13 on a rail 16, and a pair of spring-closed jaws opened by means of a handle 31. Carriage 15 is connected by a cable 33 to a cylindrical counterweight 32, slidable on a vertical rod 19, for stretching the workpiece. In the initial position, weight 32 enters a dashpot 35. Clamp 13 comprises a carriage 39 slidable on vertical rods 40, 41, not shown, a fixed jaw, and a movable jaw opened and closed by means of a handle 48. Carriage 39 is connected by a link to a pair of endless chains 54, 55 driven by a motor MD to move carriage 39 downwards and upwards. A bell crank lever 74, pivoted on carriage 39, is spring biased to engage a notch, formed therein, with any one of lugs 72 formed on respective collars 71a to 71f adjustably fixed on a vertical rod 69, to position clamp 13 in the respective cyclic-stitching positions. A gear segment on rod 69 meshes with rack teeth 84 on the armature 83 of a solenoid A, energization of which thereby turns rod 69 for disengaging a lug 72 from lever 74. A collar 86 on armature 83 simultaneously closes a microswitch MSB for operating the chains 54, 55. Carriage 39 then moves downwards until lever 74 engages the next lug 72, whereby rod 69 is moved downwards against the bias of a spring 70. A lug 82 on rod 69 thereby actuates a microswitch MSE to stop the drive to the chains, when spring 70 moves rod 69 upwards and lug 82 actuates a microswitch MSF to start the sewing machine. At the end of the stitch cycle, closure of switch MS1 energizes solenoid A for releasing lever 74 from a lug 72 and for starting the drive to the chains 54, 55. After lever 74 has been released from the lowest lug 72, a member associated with handle 48 engages a cam 88 adjustably fixed on a vertical rod 89, not shown, to open clamp 12. Clamp 14 is thereby returned with the workpiece, to its initial position by the counterweight 32. Lever 74 is also turned and latched in a position out of engagement with the lugs 72. Carriage 39 descends and then rises until, adjacent its topmost position, a pin 103 associated with lever 74 engages a fixed abutment 102 to release lever 74, whereby, after carriage 39 begins to descend, lever 74 engages the topmost lug 72, when a cam 105, not shown, on carriage 39 actuates a microswitch MSG, not shown, to stop the drive to the chains 54, 55. An emergency stop may be effected during a group-stitching operation by energization of a solenoid I. The armature 107 of the latter carries an elliptical cam member having a lower surface 126 and an upper surface 126<SP>1</SP>. Surface 126 normally overlies a pin 112 at one end of a lever 110, the other end of which is connected by a link 114 to one end of a lever 116. Link 114 is biased to a central position by opposed springs 114<SP>1</SP>,114<SP>11</SP>. The other end of lever 116 carries a pin 118 normally disposed in a notch 119 in a lever 120 biased by a spring 128 to engage a shoulder 122 therein with an arm 125 associated with the linkage 5 for holding belt 4 on the fast pulley. Momentary energization of solenoid I moves armature 107 downwards against the bias of a spring 109, whereby surface 126 engages pin 112 to move lever 110 in the direction Y, when pin 118 engages a surface 127 on lever 120 to move the latter in the direction Z. Arm 125 thereby moves from shoulder 122 to an adjacent shoulder 123 for showing the machine. On return movement of armature 107, surface 126<SP>1</SP> engages pin 112 to move lever 110 opposite to direction Y, whereby pin 118 engages a surface 127<SP>1</SP> to move lever 120 in the direction Z, and arm 125 moves to a shoulder 124 to shift belt 4 to the loose pulley. It is stated that, to prevent commencement of a sewing cycle with insufficient thread therefor, means can be provided whereby, after the completion of a predetermined number of sewing cycles, visual and audible warnings are operated.